The invention is based on a fuel feed pump for a fuel injection pump for internal combustion engines.
In such fuel injection pumps, a rotationally driven pair of gear wheels meshing with one another is provided in a pump chamber; this pair of wheels pump fuel out of an intake chamber, communicating with a supply tank, into a pressure chamber communicating with the fuel injection pump, along a feed conduit formed between the end face of the gear wheels and the circumferential wall of the pump chamber. A gear wheel is secured to a shaft and can be driven to rotate with a drive element engaging the shaft. The drive element is provided outside the pump chamber housing and transmits a rotary motion via a spur gear or Oldham coupling to a second gear wheel that meshes with the first gear wheel and is disposed on an axle supported on a housing.
Such drive elements are connected to the drive shaft in a manner fixed against relative rotation. In such gear-wheel pumps, immediately after starting, at a relatively low rpm dictated by the low rpm of the starter motor, a high supply flow is necessary so that lines and the suction chamber of the fuel injection pump will be filled quickly and put under pressure.
The known fuel feed pump has the disadvantage, however, that once an engine has been put into operation the quantity of fuel supplied by the fuel feed pump is substantially higher than the fuel quantity required for combustion. Also, if the gear wheels seize or block, damage can occur to the connection between the drive element and the driven shaft of the first gear wheel.